Requirement for PAK4 in the anchorage-independent growth of human cancer cell lines
Requirement for PAK4 in the anchorage-independent growth of human cancer cell lines
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DOI：
10.1074/jbc.m105732200
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发表时间：
2002-01-04
影响因子：
4.8
通讯作者：
Smeal, T
中科院分区：
文献类型：
--
作者：
Callow, MG;Clairvoyant, F;Smeal, T
p21激活的蛋白激酶（PAK）丝氨酸/苏氨酸激酶是Rho家族GTP酶的重要效应物，参与细胞形态和运动的调节以及细胞转化。为了进一步研究PAK激酶在肿瘤发生中的可能作用，我们分析了该家族几个成员在肿瘤细胞系中的表达。在此我们证明PAK4在多种组织来源的人类肿瘤细胞系中经常过度表达。我们还确定了丝氨酸（Ser - 474）是体内PAK4激酶结构域中可能的自身磷酸化位点。将该丝氨酸突变为谷氨酸（S474E）会导致激酶的组成性激活。当PAK4与激活的Cdc42共表达时，针对丝氨酸474的磷酸特异性抗体可在高尔基体膜上检测到激活的PAK4。此外，活性PAK4（S474E）突变体的表达具有转化潜能，导致NIH3T3细胞的非贴壁依赖性生长。另一方面，无激酶活性的PAK4（K350A，K351A）可有效阻断激活的Ras诱导的转化，并抑制HCT116结肠癌细胞的非贴壁依赖性生长。综上所述，我们的数据强烈表明PAK4参与致癌转化，并提示PAK4的活性是Ras驱动的非贴壁依赖性生长所必需的。
p2l-activated protein kinase (PAK) serine/threonine kinases are important effectors of Rho family GTPases and have been implicated in the regulation of cell morphology and motility, as well as in cell transformation. To further investigate the possible involvement of PAK kinases in tumorigenesis, we analyzed the expression of several family members in tumor cell lines. Here we demonstrate that PAK4 is frequently overexpressed in human tumor cell lines of various tissue origins. We also have identified serine (Ser-474) as the likely autophosphorylation site in the kinase domain of PAK4 in vivo. Mutation of this serine to glutamic acid (S474E) results in constitutive activation of the kinase. Phosphospecific antibodies directed against serine 474 detect activated PAK4 on the Golgi membrane when PAK4 is co-expressed with activated Cdc42. Furthermore, expression of the active PAK4 (S474E) mutant has transforming potential, leading to anchorage-independent growth of NIH3T3 cells. A kinase-inactive PAK4 (K350A,K351A), on the other hand, efficiently blocks transformation by activated Ras and inhibits anchorage-independent growth of HCT116 colon cancer cells. Taken together, our data strongly implicate PAK4 in oncogenic transformation and suggest that PAK4 activity is required for Ras-driven, anchorage-independent growth.